Navigation Flashcards
Define Great Circle
Any circle that cuts the earth in half equally
Define Small Circle
Any circle that does not cut the earth in half equally. e.g. the tropic of cancer
Define Equator
A great circle lying halfway between the poles, at the widest part of the earth
Define Parallels of Latitude
Small circles on the earths surface, the run parallel to the equator
Define Meridians
Meridians are semi-great circles running from pole to pole, they cross the equator at 90 degrees
What is the significance of Greenwich Meridian
It is is Prime meridian which is used as a reference for all other meridians
How many minutes is equal it 1 Degree
60 Minutes
Define Departure
Departure is the distance, in nautical miles, between any two places on the same parallel of latitude
How many Sea Miles are Equivalent to One Minute of Latitude
One sea mile
Define Latitude
The arc of the meridian between the equator and the parallel of latitude in question. Latitude is named North or South and is given in degrees and minutes
Define Longitude
The arc of the equator to between the Greenwich Meridian and the meridian in question. Named East or West and given in degrees and minutes.
Difference of Longitude (D’long)
The arc of the equator between two meridians
Difference of Latitude (D’lat)
The arc of the meridian between two parallels of latitude
Define Geographic Poles
The points where the spin axis cuts the earth surface, found both north and south
Define International Date Line
A semi great circle on the other side of the Greenwich Meridian which when joined forms a great circle
When Referring to a Bar Magnet do the Line of Force Go In or Out of the North Pole
In
When Referring to a Bar Magnet do the Line of Force Go In or Out of the South Pole
Out
State Newtons Laws of Magnetism
Opposite poles attract
Like poles repel
What Colour is used to Depict Magnetic North
Blue
What Colour is used to Depict Magnetic South
Red
What Simple Saying will Help Remember the Direction of Lines of Force
Out of the red, into the blue
Define Magnetic Poles
The points on the earths surface where the magnetic field is entirely vertical. Magnetic poles are not permanently fixed
Define Magnetic Equator
An irregular imaginary line, passing round the earth near the equator on which a magnetic needle had no dip
Define Variation
The angle between the true meridian and magnetic meridian, at any position on the earths’ surface.
Galaxy
A massive, gravitationally bound system that consists of stars and stellar remnants
Solar system
The sun and astronomical objects gravitationally bound in orbit around it
Star
A ball of hydrogen and helium with enough mass to sustain nuclear fusion
Planet
Celestial body that orbits the sun
Moon
A natural satellite that orbits a planet or smaller body
Equinoctial
Celestial equator
Declination
Arc of the celestial meridian, measured from the equinoctial to the body
Celestial meridian
Semi great circles on the celestial sphere
Ecliptic
Apparent path of the sun around the earth
First point of Aries
Where the ecliptic and the equinoctal intersect where the sun goes from North to South
GHA
Angle between Greewich and the body
SHA
Angle between Aries and a star
